Is the spiritual path filled with lot of stress until God’s grace is completely attained?

Ans: The feeling of stress as stress is the important point. To get a seat in a school for your son, you take lot of strenuous steps. But, you do not feel the stress at all. If you take the same strenuous steps for the sake of an outsider, you feel the stress. Therefore, stress is not the point but feeling the stress is the point. Since you have true love towards your son, you do not feel the stress.

Since you do not have true love to the outsider, you feel the stress in the same quantum of steps. Hence, the true love is responsible for your success in the spiritual path to get the divine grace of God. Kannappa did not feel any stress while plucking both his eyes for the sake of the Lord.

Dhrutarashtra knows well that Krishna is the Lord. But, he would not give even five petty villages from his vast kingdom to the Lord! The lack of true devotion is responsible for the feeling of the divine service as a stress. The spiritual knowledge generates devotion. If the spiritual knowledge is true, you will have true devotion.
At the Lotus Feet of His Holiness Sri Dattaswami

The spiritual road is filled with plenty of stress and that is a joyous thing. For one can only have this stress if they are true and faithful servants of the Father and the Son on High, for the sacrifice made in the body for our iniquity, unto salvation.

Just as the Son had gone through stress before His sacrifice, so are we to go through the same, in faith. And just as He now has life eternal after His resurrection from the dead, so will all His faithful for their devotion.

The Father grace is already attained when one takes on faith, belief, trust, and hope in the Father and Son. For He has given us redemption. Though it may be coupled with stress, it won't be forever, but His love and light will be.